Thunderbolt, 21 Piece, Black Oxide Drill Bit Set, Convenience & Heavy Duty Performance On The Jobsite, Designed For Extreme Durability & Long Life, Thicker Core Than A Standard Drill Bit To Provide Ultimate Strength & Protect Against Side Load Breakage, Specially Designed Parabolic Flute Form Clears Chips Fast, While The 3 Flat Secure-Grip Shank Holds The Bit Firmly In The Drill Chuck, 135 Degree Split Point Tip Delivers A Precision Start & Prevents Walking For Fast, Accurate Holes, For Drilling On Curved Surfaces, Require Less Effort To Drill Through Metal, Wood & PVC & Are Highly Recommended For Use With Portable Drills, Resilient Case & Includes Bit Sizes (2) 1/16", (2) 5/64", 3/32", 7/64", (2) 1/8", 9/64",5/32", 11/64", (2) 3/16", 13/64", 7/32", 15/64", (2) 1/4", 5/16", 3/8", & 1/2".